Alpha23: Easier Configuration of Push and Migration Guide

Bug Fixes

• #3577 Theme resolving doesn't work in dev mode when having a servlet path.
• #3612 Asynchronous work on generated property change listeners

Enhancements

• #480 Configuring @Push when there are only views and no UI

Breaking Changes

• #3610 UI::navigateTo method has been renamed to UI::navigate
• #3617 Add context object to beforeClientResponse calls
• #3621 Making ContinueNavigationAction class to be an inner class

Documentation Updates

• About Server Push
  • Server Push Configuration
  • Asynchronous Updates
  • Creating Collaborative Views
• Migration Guide from Vaadin 8 to Vaadin 10

All Changes

https://github.com/vaadin/flow/milestone/73?closed=1